Tube construction



Patented July 14, 1931 UNITED STATES PATENT oFI-'QIcE 'WALTERALOUIS KAHL, 0F MONTC'LVAIB, NEW JERSEY, ASSIGNOB TO .ABCTURUB RADIO TUBE COMPANY, F NEWARK, NEW JERSEY, A CORPORATION 0I DELAWARE TUBE NSTRUUlION' Application led October 31, 1927. Serial No. 228,881.

This invention relates to improvements in thermionic tube constructions and relates more particularly to vtubes of that typeA which employ a separate heating element to heat the cathode thereof.

One of the objects of the invention is to provide a tube in which the elements are supported within the tube by a minimum number of supports. Another object of the invention is to provide a tube of the heater type in which the elements are supported solely by the conducting wires for the elements. Another object of the invention is to provide a thermionic tube having four elements in which the said elements are suported solely by four conducting supports.

ther objects of the invention will be apparent as the description thereof proceeds.

One embodiment o the invention has been 2o illustrated in the accompanying drawing which represents a perspective view of a thermionic tube with a portion of the envelope broken away to disclose the construction thereof.

The invention is an improvement over the thermionic tube construction shown and described in my copending application, Serial No. 140,245 in which the elements ofthe tube comprise a plate or anode, a rid or 3o control electrode, a cathode forme of a cylindrical shell coated with an electronemitting oxide and a heater element disposed axially within the shell and separated from the shell by space without any solid 85 di-electric. In the application above referred to, the elements were shown positioned by a number of supports, this number being in excess of the actual number of conductors leading from the elements. The

4o present invention limits the number of supports to one support for each element, this being the actual number of electrical conductors necessary.

Referring more specifically to the draw- 48 ing, the tube comprises a shell 10 which may be mounted upon a base 11 and which ma have, sealed to its smaller end, the stem 12 having a press 13 at its upper end through which the conductors for the elements pass and in which they are sealed. A plate 14 is bent in the form of a cylinder and may be provided with flanges 15 at the adjoining ends thereof which may be welded or otherwise attached to a relatively heavy conductor support 16 which is sealed in the press 13 and extends upwardl along the entire length of the plate. forms a rigid sup ort for the plate.

he grid may preferably be formed .of a spiral coil of wire`17 which is welded at one side to a spacing rod 18 and at the other side to a support rod 19 which extends beyond the ends of the coil 17. The support rod 19 may be bent outwardly at the lower end thereof and welded to another relatively large conductor 20 which is sealed into the press 13 at the side opposite from the conductor 16.

The cathode comprises a cylinder 21 preferably being a conductor with a low resistance and being coated with an electronemitting oxide as is clearly explained in the application above referred to. The cathode preferably extends somewhat above and below the plate and grid and the lower end thereof is welded to a support rod 22 which is also sealed into the press 13. A convenient way of welding the cathode to the support rod 22 is to bind the two together with a metal ribbon 21a welding the three into a rigid connection. An auxiliary support rod 23 is welded tothe rod 22 at right angles thereto and extends outwardly some distance beyond the plate and is then bent upwardly to a point above the to of the plate where it is again bent inwar l a short distance for a purpose to be hereinaer described. The upper end of the cathode is attached to this support 23 adjacent its upper end by means of a strip 24 which may be bent around the top of the cathode and welded thereto so that the free ends extend outwardly toward the support 23 to the upper end of which they may e welded.

The heater element may comprise a s' le 95 y rod or lament 25 which is attached at lts lower end to a conductor 26 in any desired manner. The conductor 26 is in turn welded to a conductor sup ort 27 which is sealed in the press 13 and orms the conductor and 10o support for the lower end of the filament 25. The upper. end of the filament 25 1s attached in a like manner to a conductor 28 which is supported by a thinrsprmg 29 attached to the inturned upper end of the support 23. The spring 29 forms a means to compensate for expansion and contraction of the heater filament.

A glass bead 30 -is sealed on to the sup- .port 23 about mid-way of the vertical part thereof and a short angular support 31 is sealed into the bead 30 at one end and` has its other end welded to the upper end of the conductor support 16 or it may be attached to the plate 14 in any desired man ner. Another angular support 32 is sealed into thevother end of the glass bead 30 and extends upwardly and outwardl to preferably the upper end of the con uctor support 19 to which it is welded in order to rigidly support the upper end of the grld.

The conductors 16, 27, 22 and 20 are connected respectively by wires 33, 34, 35 and 36 which may be attached to the base terminals to conform with the standard practice of connecting the terminals on a direct current tube.

It will thus be seen that the plate 14 is connected through the conductor support 16 and connection 33 to the plate terminal 37. In like manner, the grid 17 is connected by means of the support rod 19 and conductor support 20 through wire 36 to the grid terminal 38. The other two terminals 39 and 40 are connected to the wires 34 and 35 which lead through the conductors 27 and 22 respectively to the lower and upper ends of the heater element. It will be noted that the path of the current between the wire 35 and the upper end of the filament may pass through both the conductors 23 and the low resistance cathode.

From the above it will be apparent that I have provided a thermionic tube construction in which the elements are supported by the fewest possible supports, each of these supports forming a conductor for one of the elements thereof. This construction provides not onl an inexpensive structure which is manu actured out of relatively few parts, but affects great saving in the labor necessary to assemble the tube. It will also be noted that the tube is provided with a standard base which may be placed in a standard socket and that the tube has no external or additional elements which would necessitate extra wiring and additional circuits.

While I haveAA shown one embodiment of the invention in the drawing, I do not desire `to limit myself to the specific construction shown, but to interpret the invention broadly within the scope of the appended claims.

Having thus described my invention, what I claim is:

cathode; a fourth conductor supporting the lower end of said heating element'and sealed in said press, said heating element and cathode being electrically connected together at the upper end thereof; and means to rigidly support in spaced relation the upper ends of said plate, grid, cathode and heater element, said means being supported upon one of said conductors.

2. In a thermionic tube, a press; a cylindrical plate; a conductor sealed in said press and supporting said plate; a cylindrical grid Within said plate; a second conductor sealed in said press and supporting said grid; a cylindrical cathode within said grid; a third conductor sealed in said press and supporting said cathode; a single straight heater element within the cathode; a fourth conductor sealed in said press and supporting said heater element; a support attached to.

one of said conductors and extending upwardly on the outer side of said plate; an insulating body attached to said support; and a plurality of additional supports attached to said insulating body and positioning in spaced relation the upper ends of said plate, grid, cathode and heater element, the upper ends of said cathode and heater element being electrically connected together.

3. In a thermionic tube, a stem having a slngle press therein; a conductor sealed in said press; a cylindrical cathode attached at itsllower end to said conductor; a support also attached to said conductor and extending outwardly and upwardly to a point substantially even with the upper end of sald cathode; a connector between the upper en d of said cathode and the upper end of said support; a single straight heating element within said cathode and substantially on the axis thereof; a conductor attached to the lower end of said heating element and sealed in said press; a spring attached to the upper end of said heating element and supported on the upper end of said support; an insulating block attached to said support; a substantially cylindrical grid surrounding said cathode and substantially concentric therewith; a conductor attached to the lower end of said grid and sealed in ysaid press; a connector supporting the upper end of4 said grid from said insulating block; a substantially cylindrical plate surrounding said grid and concentric therewith; a conductor sealed in said press and attached to said plate; and a connector between the upper end of said plate and said insulating block.

4. In a thermionic tube, an anode; a grid; a cathode; and a heater for said cathode, said cathode and heater being electrically connected together; separate conductors attached to `each end of said heater, and to one end of said grid and said plate respectively said conductors being sealed into said stem; means to support in spaced relation the upper ends of said plate, grid, cathode and heater, said means together with all of said elements being supported solely upon said conductors. f

5. In a thermionic tube comprising an envelope and a base, said envelope containing electrodos consisting of an anode, grid, cathode and heater in spaced relation, said heater adapted to be energized by alternating or uctuating current; four terminals on sald base, said base andterminals being so arranged as to ft into a socket adapted for use Wlth direct current tubes; means to support the upper ends of said anode, gud cathode and heater in spaced relation; and means to support all of said electrodes and said spacing and supporting means solely upon the conductors therefor. so In testimony whereof, I ax my signature.

WALTER LOUIS KRATIL. 

